Question

An office building is served by an air-cooled chiller currently operating at 115 tons (404.5 kW). The measured chilled water supply temperature is 43°F (6.1°C), and the measured chilled water return temperature is 57°F (13.9°C). What is the estimated chilled water flow rate through the chiller? A. 172 gpm (10.9 L/s) B. 197 gpm (12.4 L/s) C. 212 gpm (13.4 L/s)

Answer 1

Answer:

B.197 gpm and 12.4 L/s

Explanation:

Given that

Load Q = 404.5 KW

Water inlet temperature= 6.1 °C

Water outlet temperature= 13.9°C

We know that specific heat for water

$C_p=4.187\ \frac{KJ}{kg.K}$

Now from energy balance

$Q=\dot{m}C_p\Delta T$

by putting the values

$Q=\dot{m}C_p\Delta T$

$404.5=\dot{m}\times 4.187(13.9-6.1)$

$\dot{m}=12.38\ \frac{kg}{s}$     (1 Kg/s = 15.85 gal/min)

We can say that

$\dot{m}=196.31\ \frac{gal}{min}$

We know that

$\dot{m}=\rho\times volume\ flow\ rate$

12.38=1000 x volume flow rate

$volume\ flow\ rate\ = 12.38\times 10^{-3}\ \frac{m^3}{s}$

So

volume flow rate = 12.38 L/s

So the option B is correct.